1. Field of the Invention
The present invention relates to a fuel tank for use in a motor vehicle.
2. Description of the Related Art
A motor vehicle driven by an internal combustion engine is normally equipped with a fuel tank. When it becomes necessary to replenish the fuel tank with fuel, the cap attached to the fuel inlet of the fuel tank must first be detached, to allow the insertion of a fuel pump nozzle. After the fuel pump nozzle is inserted into the fuel inlet of the fuel tank, fuel is fed into the fuel in the fuel tank from the fuel pump nozzle. However, when the level of the fuel in the fuel tank is low, the space in the fuel tank above the surface of the liquid fuel is filled with a large amount of fuel vapor under pressure. Consequently, when the cap is detached from the fuel inlet of the fuel tank, the fuel vapor in the fuel tank is forced out of the fuel tank into the outside air, causing air pollution. In addition, when fuel is fed into the fuel tank from the fuel pump nozzle, the fuel spouted from the nozzle comes into violent contact with and agitates the fuel in the fuel tank, causing bubbles to form in the fuel in the fuel tank. The collapsing of these bubbles causes further amounts of fuel vapor to be generated in the fuel tank, and this fuel vapor escapes from the fuel inlet of the fuel tank, causing more air pollution.
Japanese Unexamined Patent Publication (Kokai) No. 56-128221 discloses a fuel tank in which a fuel storing chamber completely surrounded by an expansible bellows is formed on the inner bottom wall of the fuel tank, and the fuel inlet pipe is connected to the fuel storing chamber. In this embodiment, it is possible to reduce the amount of fuel vapor escaping to the outside air when the cap is detached from the fuel inlet of the fuel inlet pipe. However, in this embodiment, it is impossible to discharge the fuel vapor stored in the bellows to the exterior of the bellows, and thus there is a problem in that a satisfactory large storing volume for fuel can not be obtained in the tank.